Have you ever noticed that the screen on your device (whether on your computer or iDevice) changes to somewhat of a bluish color at night? It tends to be a bright bluish glow that can at many times be blinding. This is a result of how the screen is engineered. This bluish glow or color temperature is in place to make viewing during the day much easier. The screens are supposed to behave like the sun so there's not a ton of strain on your eyes - basically, it adds a lighted setting so that the differences in lighting don't affect your eyes. However, when you use your computer or device at night, the scenario is totally different. Despite the blinding factor of the bluish light, studies have shown that this color temperature (the one that the bluish glow emits) can also be damaging to your health at night. Blue light is beneficial for your circadian rhythm (what keeps your body on a 24-hour schedule) during the day, however at night, it has negative effects. It can keep you up awake later at night as well as ruin the quality of your sleep. Sleep researchers have been studying the effects of devices such as cell phones, computers, and mobile tablets, finding evidence that this is truly the case.

Now you may be thinking that turning down the brightness is an obvious alternative. That is not the case - the bluish glow and the effects it has at night time is still present even when the brightness is turned down.

A company called F.lux created a piece of software (patent pending) called f.lux that can be installed on your computer (Windows, OS X, Linux) to make your screen's light adapt to the time of day. So during the day, the lights that are displayed as well as the color temperature is different from what is at night. With this ground-breaking technology, you are able to use your computer during any time of the day without having to worry about strain or negative effects on your body. F.lux just recently made their software available for iOS users through Cydia.

After installing f.lux from Cydia, you can change all the settings directly from inside the Settings pane. Inside the Settings tab for f.lux, you have a few options:

At night - choose which type of bulb or lightning situation you are in so that f.lux adapts when it is night time (based upon the clock)

Transition speed - change the transition speed from day to night (on older devices, it is instant to avoid flickering)

Color-sensitive work - turn f.lux on or off

There is nothing else to configure outside of just these settings.

The Cydia description is highly comprehensive and explains a ton of useful information about this application. I recommend that you read this thoroughly if you find this tweak of interest to you. The description does make sure to alert you of a few things:

f.lux does have a minor impact on your battery life

The current version of f.lux requires Location Services to be enabled. If you happen to install it when Location Services are turned off, you must reboot or re-install it for it to work

Although Locations Services is required, we do not track your information and have no servers on our end that capture information

iPhone 3G support is still experimental at this point

If you're looking to improve your health and never have to deal with being blinded or emitting that bluish glow at night, than give this one a shot! It's free on Cydia and is available on all devices and firmwares on 4.x.

Name: f.luxAuthor: F.lux Software LLCVersion: 0.94Price: Free

To find out more information about the company F.lux and their other products, visit the F.lux website. And if you don't believe the "studies" that were mentioned in the article, read up on the F.lux website. They have article upon article with extensive research evidence that validates their argument and why their product is legitimate.

You have to remember that the way the tweak behaves is based upon the sun and night light. Locations Services are used to determine how the tweak is effectively working on your device. Location is key when it comes to switching to a different light, that sort of thing.

Blue light tells our body its daytime and to be awake and alert. lack of blue light triggers chemicals that makes us sleepy and tells us its time to rest. Office lighting is usually neutral white and not warm white, to keep employees awake and alert. Home lighting is usually warm white to create a comfortable feeling and allow us to keep our sleep cycle. You can have cool white or neutral white in your home but your bedroom should be warm white. The backlight in most of our electronic devices use white LEDs, or white CCFL. White LED is made from blue LED, just coated with phosphor to create white light. Turning the LCD a warmer shade may help but im not sure how effective this is. Certain wavelength of blue might still get through. You can just use your monitor setting to turn the screen warm white without special apps or software. If you are worried about computer screen ruining your sleep, its best to just limit your computer/TV/phone usage at night.

I'm no light bulb expert, but I put this on my Mac too to see how it works. Hopefully I'll understand it more as the time for the screen change comes.

The differences in light bulb generally mean the shape (that's at least what I use to determine). You're mostly around fluorescent bulbs these days due to energy regulations and the value you get out of saving.

Originally Posted by snap1500

Blue light tells our body its daytime and to be awake and alert. lack of blue light triggers chemicals that makes us sleepy and tells us its time to rest. Office lighting is usually neutral white and not warm white, to keep employees awake and alert. Home lighting is usually warm white to create a comfortable feeling and allow us to keep our sleep cycle. You can have cool white or neutral white in your home but your bedroom should be warm white. The backlight in most of our electronic devices use white LEDs, or white CCFL. White LED is made from blue LED, just coated with phosphor to create white light. Turning the LCD a warmer shade may help but im not sure how effective this is. Certain wavelength of blue might still get through. You can just use your monitor setting to turn the screen warm white without special apps or software. If you are worried about computer screen ruining your sleep, its best to just limit your computer/TV/phone usage at night.

Definitely - it is generally a bad idea to expose yourself to devices late at night for this very reason. However, in the early parts of the night (such as early dusk and evening), it's not as bad as when it's extremely late. And if you have to be up late for various reasons, it can be a better experience.

Installed it and enjoying it so far. Would be great if you could enter a custom value in Kelvins like you can with their desktop version. The lighting in my room is not as yellow as incandescent, but warmer than halogen.